Camera flips 180 degrees following the path
Nice car, that's my favourite one... so applying scale of the curve doesn't helps. 

That was just a guess, I already thought that my idea wont work....

So well, your curve flows like that: sometimes the curve is over the handles and sometimes under them. On the place were the cam switches, the curve is at two places over the handles (so like Adrian Monk would Say it's not perfectly symmetric...) I checked with the fishbones the directions of your curve, but it looked okay...

Sometimes I'm a bit confusing, sorry for that!